Astronomers first look at the atmosphere of a brown dwarf

Astronomers first look at the atmosphere of a brown dwarf
Astronomers first look at the atmosphere of a brown dwarf
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The new algorithm allowed us to reconstruct the atmosphere of the brown dwarf Luhman 16B, which is close to us, showing that, in general, it is similar to the atmosphere of Jupiter.

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Brown dwarfs are intermediate between planets and stars. Gaining a mass of several tens of Jupiter's masses, they are not able to launch thermonuclear reactions of proton fusion in their bowels. They glow weakly and cool down rather quickly (although there are some exceptions), so it has not yet been possible to directly observe what is happening on brown dwarfs.

Daniel Apai and his colleagues at the University of Arizona examined the atmosphere of such an object for the first time using data from the TESS space telescope. They talk about their work in an article published in The Astrophysical Journal. None of the existing telescopes can see such a target directly, so scientists have developed a new data processing algorithm that allows you to approximately reconstruct the appearance of the atmosphere from the luminosity of a brown dwarf.

The object of research was the closest pair of brown dwarfs Luhman 16 AB, located only 6.5 light years away. The dimensions of both are approximately equal to Jupiter, but one (16 A) is 34 times more massive than it, and the second (16 B, which scientists have considered) is 25 times more massive. Scientists analyzed the ultra-precise TESS data on the change in the luminosity of Luhman 16 B, which occurs as the binary system rotates, covering about a hundred revolutions.

This made it possible to determine several periods of time over which the brightness of the brown dwarf changes, substituting for us now darker areas of its surface - thick cloudiness, or light stripes - relatively thin clouds through which weak radiation from the bowels breaks through. Wide dark and light streaks of strong and stable winds sweep it parallel to the equator.

The speed of these winds decreases closer to the poles. Their surroundings are dominated by more chaotic, funnel-forming hurricanes. Thus, the atmospheres of brown dwarfs resemble those of gas giants such as Jupiter. Their dynamics is determined not by the mass of local, individual hurricanes, but by global patterns of winds that cover the entire planet.

“By measuring the changes in brightness of such rotating objects over time, it is possible to make rough maps of their atmospheres,” concluded Daniel Apai. "In the future, this technique will also be used to map terrestrial planets in other systems that are difficult to see with other methods."

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